Indirect exhaust system



Jan. 2, 1934. A. R. CLARK INDIRECT EXHAUST SYSTEM Filed July 29, 1952 gwue wtoz W W d tw g mm H? MY amt/"41 5 Patented Jan. 2, 19 34 m'rau orFieE 1,942,048 a v INDIRECT EXHAUST SYSTEM Albert R. Clark, Toledo, Ohio, assi'gnor toThe De Vilbiss Company, Toledo, Ohio, a corporation of Ohio Application July 29, 1932. Serial No. 625,785

8 Claims.

This invention relates to an indirect exhaust system in which air is induced to fiow'through the exhaust conduit by the injection of entraining air under pressure into the conduit in the dimotion in which itis desired to have the exhaust flow. It has been developed primarily for use in exhausting-the poisonous fumes from a paint spray booth, but obviously it is capable'of use in other relations.

The general object of the invention is to improve the efiiciency, or in-other words, to increase the volume'of flow as" compared to the power consumed; while'retaining the desirable features of the system which tend to prevent particles of paint from'lodgingwithinthe conduit. in this respect, the invention is an improvement over U. S. Patent No; 1,701,637, issued February 12, 1929, to Harold A. Roselund;

With the above object in view, the invention comprises the combustion of a-venturi with the exhaust passage, andthe further modification oi the latter ina manner to promote the air flow and to completetne mixture of the paint spray with entraining air at the proper point for producing the best results.

Theinvention will be more specifically described in connection with the accompanying drawing which illustrates the preferred form thereof and in which Fig. l is a vertical sectional view thereof with the air passageways shown partially in side elevation;

Fig. 2 is a section taken on the line 2--2 of Fig; 1;

Fig. 3 is an enlarged detail sectional view of the connection between the induction conduit and the outlet from the spray booth.

The invention is illustrated in connection with abooth 5'within which the painting isdone. The rear wall 6 of this booth is preferably spaced far enough from the outer wall '7 to provide a suitable space for installing the exhaust system.

In the form illustratedin the drawing, a motor 8 is mounted on a base 9 in rear of the booth and drives a shaft 10 which operates a blower within the casing 11.

The exhaust'passageway from the booth 5 is circular in cross section and comprises a mouth 12 which'is tapered at an angle of approximately 22. The portion 18 of the exhaust passageway is cylindrical and leads'from the mouth 12 to a portion 14 which is associated with the outlet from the blower casing 11 and which is tapered at an angle of approximately 6. The area of the intake end of the mouth 12 is approximately 1% times the cross sectional. areaofportion" 13 of the-passageway. 7

The blower casing-11 has an intake 15, prefer.- ably from outside the building, and an outlet 16 which-leads into an annular chamber l7-disposed" about the tapered portion 14 of theexhaust passageway.

The chamber 17 is provided with a restricted annular outlet or nozzle 18 extending about the tapered outlet 140i the exhaust'passage, to which it is secured, preferably by bolts 19-and-spacing sleeves 20. Thus the-entraining air is discharged; under pressure from the chamber 1'7 in a thin annular streamwhich is tapered at an angle of approximately 6 into a passageway which is similarly tapered, as at 21, to form a venturi 22'. Fromthe venturi the passageway flares outwardly at an angle of approximately 6 to the point indicatedat 26. Here is located the-apex of the cone which would-be formed if the tapered surface of the wall 21 were continued. At this point, therefore, there is a'substantially-complete intermingling of the spray from the booth 5 and the entraining air from the blower 11. a This resultsin a maximum flow of the exhaust airfrom the booth, which is'carried for a short distance through a cylindricalcasing 2'7, whence it'is discharged into the atmosphere through a mouth 28, which is flared at an angle of approximately 5 13 8 In accordance with the preferred construction,- the cross sectional areaof the venturi 22 is somewhat more than one-half the cross sectional area of the passageway 12 in the smaller sizes and proportionately somewhat less in the larger sizes. The crosssectional area of the cylindrical casing 27 is substantially greater thanthat of the passageway 13; its proportion being greater for the smaller sizes.

In order to promote the uniform distribution of the air under pressure .as it flows from the chamber 17 through the nozzle 18, this chamber is provided at each side with an inclined defiector plate 23 whichextends across'the annular chamber and approximately halfway of the length thereof; so that half of the air is discharged into the lower part of thetapered passageway-21, while the remainder of the air is carried upwardly and deflected by a vertical deflector plate 2% at the'top of the chamber and extending throughout the length thereof.

In theoperation of my improved system, the venturi 22,'the tapered mouth 12, the tapered passageways 14 and 21, the deflectors 23'and 24, the flared'passageway 25- and the flared outlet mouth 28 all contribute more or less to its increased efficiency as compared to other systems. These features may, however, be modified and some of them may be omitted altogether without departing from the scope of the invention as claimed.

What I claim is:

1. In an indirect exhaust system, an exhaust passageway having a uniformly tapered discharge end portion, a chamber about said tapered portion and provided with a discharge nozzle concentric with and slightly larger than the extremity of said end portion, means for supplying air under pressure to said chamber, and a discharge passageway connected with said nozzle and tapered at substantially the same angle as the exhaust passageway to form a venturi, the discharge passageway gradually increasing in size from the venturi toward the outlet end and then continuing in a cylindrical portion, the beginning of said cylindrical portion being in the region where the convergent lines of the tapered passageway would meet if produced.

2. In an indirect exhaust system, an exhaust passageway, a nozzle about the outlet end of said passageway, means for supplying air under pressure to said nozzle for entraining air from said passageway, and a discharge passageway connected to said nozzle and tapered to form a venturi, the discharge passageway gradually increasing in size from the venturi toward the outlet end and then continuing in a cylindrical portion, the beginning of said cylindrical portion being in the region where the convergent lines of the tapered passageway would meet if produced.

3. In an indirect exhaust system, an exhaust passageway having a uniformly tapered discharge end portion, a chamber about said tapered portion and provided with a discharge nozzle concentric with and slightly larger than the extremity of said end portion for entraining air from the exhaust passageway, means for supplying air under pressure to said chamber, and a discharge passageway connected to said nozzle and formed with a venturi, said discharge passageway being tapered from the nozzle to the venturi at substantially the same angle as the exhaust passageway, the discharge passageway gradually increasing in size from the venturi toward the outlet end and then continuing in a cylindrical portion, the beginning of said cylindrical portion being in the region where the convergent lines of the tapered passageway would meet if produced.

4. In an indirect exhaust system, an exhaust passageway having a uniformly tapered discharge end portion, a chamber about'said discharge end portion and provided with a tapered discharge nozzle concentric with and slightly spaced from said discharge end portion to form a restricted outlet and extending beyond the same to form a discharge passageway with a venturi, means for supplying air under pressure to said chamber, the discharge end of said nozzle and the wall of said discharge passageway from the nozzle to the venturi being uniformly tapered at substantially the same angle as the wall of the exhaust passageway and cooperating with the latter to emit and direct a thin annular stream of air along the surface of the discharge passageway, said discharge passageway being continued and gradually increasing in size from the venturi toward the outlet end.

5. In an indirect exhaust system, an exhaust passageway having a uniformly tapered discharge end portion, a chamber about said discharge end portion and provided with a tapered discharge nozzle concentric with and slightly spaced from said discharge end portion to form a restricted outlet and extending beyond the same to form a discharge passageway with a venturi, means for supplying air under pressure to said chamber through the side thereof, deflectors between the inlet side of said chamber and the opposite side to distribute the air about said nozzle, the discharge end of said nozzle and the wall of said discharge passageway from the nozzle to the venturi being uniformly tapered at substantially the same angle as the wall of the exhaust passageway and cooperating with the latter to emit and direct a thin annular stream of air along the surface of the discharge passageway, said discharge passageway being continued and gradually increasing in size from the venturi toward the outlet end.

6. In an indirect exhaust system, an exhaust passageway having a uniformly tapered discharge portion, a chamber about said tapered portion and provided with a wall converging toward but terminating short of the extremity ofsaid discharge end portion, a dischargenozzle forming a continuation of said convergent Wall, means for supplying air under pressure to said chamber through the side thereof, a partition disposed longitudinally of the chamber on the side opposite the air inlet thereto, deflectors extending part way of the length of the chamber between said inlet and said partition to direct air through the nozzle, and a discharge passageway constituting a continuation of said nozzle and formed with a venturi, said nozzle and the wall of said discharge passageway from the nozzle to the venturi being tapered at substantially the same angle as the wall of the exhaust passageway and cooperating with the latter to direct a thin annular stream of air along the surface of the discharge passageway, said discharge passageway gradually increasing in size from the venturi toward the outlet end. v

'7. In an indirect exhaust system, an exhaust passageway having a uniformly tapered discharge end portion, a chamber about said tapered portion and provided with a wall converging toward but terminating short of the extremity of said discharge end portion, a discharge nozzle forming a continuation of said convergent wall for entraining air from the exhaust passageway, means for supplying air under pressure to said chambar, and a discharge passageway constituting a continuation of said nozzle and formed with a venturi, said nozzle and the wall of said discharge passageway from the nozzle to the venturi being tapered at substantially the same angle as the exhaust passageway and cooperating with the latter to direct a thin annular stream of air along the surface of the discharge passageway, the di-' ameter of the discharge passageway uniformly increasing from the venturi toward the outlet end untilit is materially greater than the greatest diameter of said exhaust passageway.

8. In an indirect exhaust system, an exhaust passageway having a uniformly tapered discharge end portion, a chamber about said tapered portion and provided with a discharge nozzle concentric with and slightly spaced from said discharge end portion to discharge a thin annular stream of air for entraining air from the exhaust passageway, means for supplying air under pressure to said chamber, and a discharge passageway forming a increasing in diameter for a distance from the venturi toward the outlet and then continuing in a cylindrical portion having a diameter considerably greater than the greater diameter of said exhaust passageway.

ALBERT R. CLARK. 

